// Copyright 2015 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef BASE_FILES_FILE_TRACING_H_
#define BASE_FILES_FILE_TRACING_H_

#include <stdint.h>

#include "base/base_export.h"
#include "base/macros.h"

#define FILE_TRACING_PREFIX "File"

#define SCOPED_FILE_TRACE_WITH_SIZE(name, size) \
    FileTracing::ScopedTrace scoped_file_trace; \
    if (FileTracing::IsCategoryEnabled())       \
    scoped_file_trace.Initialize(FILE_TRACING_PREFIX "::" name, this, size)

#define SCOPED_FILE_TRACE(name) SCOPED_FILE_TRACE_WITH_SIZE(name, 0)

namespace base {

class File;
class FilePath;

class BASE_EXPORT FileTracing {
public:
    // Whether the file tracing category is enabled.
    static bool IsCategoryEnabled();

    class Provider {
    public:
        virtual ~Provider() = default;

        // Whether the file tracing category is currently enabled.
        virtual bool FileTracingCategoryIsEnabled() const = 0;

        // Enables file tracing for |id|. Must be called before recording events.
        virtual void FileTracingEnable(void* id) = 0;

        // Disables file tracing for |id|.
        virtual void FileTracingDisable(void* id) = 0;

        // Begins an event for |id| with |name|. |path| tells where in the directory
        // structure the event is happening (and may be blank). |size| is the number
        // of bytes involved in the event.
        virtual void FileTracingEventBegin(const char* name,
            void* id,
            const FilePath& path,
            int64_t size)
            = 0;

        // Ends an event for |id| with |name|.
        virtual void FileTracingEventEnd(const char* name, void* id) = 0;
    };

    // Sets a global file tracing provider to query categories and record events.
    static void SetProvider(Provider* provider);

    // Enables file tracing while in scope.
    class ScopedEnabler {
    public:
        ScopedEnabler();
        ~ScopedEnabler();
    };

    class ScopedTrace {
    public:
        ScopedTrace();
        ~ScopedTrace();

        // Called only if the tracing category is enabled. |name| is the name of the
        // event to trace (e.g. "Read", "Write") and must have an application
        // lifetime (e.g. static or literal). |file| is the file being traced; must
        // outlive this class. |size| is the size (in bytes) of this event.
        void Initialize(const char* name, File* file, int64_t size);

    private:
        // The ID of this trace. Based on the |file| passed to |Initialize()|. Must
        // outlive this class.
        void* id_;

        // The name of the event to trace (e.g. "Read", "Write"). Prefixed with
        // "File".
        const char* name_;

        DISALLOW_COPY_AND_ASSIGN(ScopedTrace);
    };

    DISALLOW_COPY_AND_ASSIGN(FileTracing);
};

} // namespace base

#endif // BASE_FILES_FILE_TRACING_H_
